Underwater replaceable reference electrode

ABSTRACT

A series of layers of silver gauze are welded to a central silver nut to form a reference electrode. The electrode is threaded onto the end of a silver-plated phosphor bronze connecting rod which extends through a ship&#39;&#39;s hull by way of a waterproof stuffing tube. Interposed between the hull and the electrode is an insulating layer with the electrode spaced therefrom while the rod is provided with an electrically insulating outer layer to minimize the development of undesirable potentials between the rod and the stuffing tube. A holder cover is situated over the reference electrode, permitting free flooding of the area proximate the electrode without excessive turbulence so that the electrode can be employed to monitor and control the impressed cathodic protection system of the ship.

United States Patent [72] Inventor Isidore Geld 3,272,731 9/1966Hutchison et al 204/195 Flushing, NY. 3,408,280 10/1968 Preiser 204/196[21] Appl. No. 879,478 3,410,772 11/1968 Geld et al. 204/196 [22] FiledNov. 24, 1969 3,501,392 3/1970 Ayers 204/195 [45] Patented Dec. 7, 1971Prim y Exammer-T. Tung [73 1 Asslgnee The United i h N Attorneys-RichardS. Sciascia, Louis B. Applebaum and represented by t e fetal-ya t eErnest F. \v einberger [54] UNDERWATER REPLACEABLE REFERENCE ABSTRACT: Aseries of layers of silver gauze are welded to a ELE( :TRDE centralsilver nut to form a reference electrode The electrode Dnwmg Flgs isthreaded onto the end of a silver-plated phosphor bronze [52] 11.8. CI204/196, connecting rod which extends through u ships hull by way otu204/1 T, 204/195 waterproof stuffing tube. lnterposed between the hulland the [51] Int. Cl ..C23f13/00, electrode is an insulating layer withthe electrode spaced GOln 27/30 therefrom while the rod is provided withan electrically insu- [50] Field of Search 204/ 1 T, lating outer layerto minimize the development of undesirable 147, 195, 196 potentialsbetween the rod and the stuffing tube. A holder cover is situated overthe reference electrode, permitting free 1 References Cited flooding ofthe area proximate the electrode without excessive UNITED STATES PATENTSturbulence so that the electrode can be employed to monitor 2,910,419/1959 Preiser et a1. 204/196 and control the impressed cathodicProtection system of the 2,910,420 10/1959 Preiser 204/195 3,l29,16l4/1964 Anderson et a1 204/195 3 52 j? fix j/ 45 55 44 45/20 22 39 f0 34tntmj l h a5 1 1, 40 I ,1 35 35 i A 1 r /0 3a ,1 1 y If, I 1 X oPATENTEU DEC 7 IQTI SHEET 2 BF 2 INVENTOR. [5/0025 651.0 Ki 2 wmfim w 9770535 Y5 UNDERWATER REPLACEABLE REFERENCE ELECTRODE The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to an impressed current cathodic protection system forthe hull of a metallic ship, and more particularly pertains to anunderwater reference electrode wherein the electrode can be replacedwhile the ship is in the water without any possibility of hull leakage.

2. Description of the Prior Art In the field of automatic impressedcurrent cathodic protection systems, it has been the general practice toemploy a previously installed spare reference electrode when the primaryelectrode has deteriorated or has become unserviceable for any reason.In the event the spare should fail, the system must be controlledmanually instead of by the reference electrode, which provides thecontrol sensing element until the ship is drydocked. Another referenceelectrode structural arrangement is presently available wherein thespent electrode element is ejected out of the stuffing gland into theocean from inside the ship. However, the problem of leakage has not beencompletely solved and the stuffing gland may require replacement, sinceit does not always mate properly with the new electrode. Thus, thisarrangement can not be used under deep submergence conditions such as insubmarines.

SUMMARY OF THE INVENTION The general purpose of this invention is toprovide a replaceable reference electrode that has all the advantages ofsimilarly employed prior art devices and has none of the above describeddisadvantages. To attain this, the present invention provides a uniquestructural reference electrode arrangement wherein the gauze layeredelectrode elements are welded to a silver nut which is affixed to thethreaded end of a silverplated bronze rod extending from within theship. The rod is covered with an electrical insulator to minimize anypotential between the rod and the stuffing tube.

An object of the present invention is to provide a reference electrodestructure for mounting on a ship's hull the reference electrode being soconstructed that it can be readily replaced underwater withoutdisturbing the watertight integrity of the hull.

Another object is to provide a simple, inexpensive, reliable andreplaceable reference electrode suitable for use as the sensing elementin an automatic impressed current cathodic protection system.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevation of anembodiment made in accordance with the principle of this invention; and

FIG. 2 is a plan view of the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment of FIG. I theships hull is provided with an aperture 11 in which is fitted one end ofa stuffing gland body 12 that is welded in this position to the hull,the aperture I1 being aligned with the aperture 13 of the fiber glassholder base 14. When the base 14 is afiixed to the hull, it is set in alayer of epoxy putty 15 which completely fills the area between the hulland the holder base to eliminate any voids or air pockets. Thecylindrical passage 16 of the body is open from end to end and at theend that is anchored to the hull it is aligned with the aperture 13 inthe holder base I4. The passage 16, intermediate of its ends, has ashoulder 17 facing the free end of element or body 12 and is larger indiameter from the shoulder 17 to the free end of the body 12. A tubularliner sleeve 18 of electrically insulating material fits the aperture 13of the holder 14 and the passage 16 from the base holder 14 to theshoulder 17.

A rod or pin 19 of electrically conducting material such as phosphorbronze or other suitable metal is provided with an insulating coatingover an outer silver plating. The insulating coating can be a generalpurpose epoxy and need only extend between the upper threaded portion 20and the lower threaded portion 21. The purpose of this coating is toprevent the generation of any potential between the pin 19 and the body12 upon the intrusion of sea water. A rectangular washer 22 is welded orbrazed on to the pin 19 so as to prevent turning of the pin when thereference electrode is threaded thereon. The washer 22 is coated with anepoxy for the same reason as the reason for coating the pin. Packingmaterial 23 of electrically insulating material is disposed around therod I9 in the larger diameter part of the passage and abuts against theshoulder 17. This packing material may be V-packing rings of syntheticrubber, abutting end to end and against shoulder 17. The tubularstuffing gland 24 is threaded into the free end of body 12 to abutagainst the outer end face of the packing material 23 and to compress itagainst shoulder 17 and thereby deform such material against the wall ofthe passage and against the rod 19.

Another liner sleeve 25 of electrically insulating material fits the rod19, outwardly beyond the packing means, and also the passageway of gland24 to the outer end of the gland. An electrically insulating washer 26fits over the rod 19 and abuts the other end of liner sleeve 25 and theouter face of the gland 24. A nut 27 is threaded on the rod 19 toconfine the washer 26 against the outer end of the gland 24. A secondwasher 28 of electrically insulating material is fitted over the end ofrod 19 to abut against the outer face of nut 27. A metallic eupshapedcollar or member 29 is threaded over the exterior of the free end ofbody 12 and has an aperture 30 in its end through which the rod 19loosely passes, with the inner face of this end abutting against thewasher 28 to confine it against the nut 27. A liner sleeve 31 surroundsthe rod 19 and passes through the aperture 30, abuts washer 28 andextends outwardly away from the member 29, but does not extend entirelyto the free end of the rod 19. A metal terminal connector 32 has anaperture through which the threaded free end of the rod 19 extends andthe nuts 33 threaded on the end of the rod 19, on opposite sides ofterminal 32, enable the terminal to be confined on the rod 19 againstthe outer end of liner sleeve 31. The terminal 32 is connected by wire34 to the control device of the cathodic protection system.

Hull studs 35 extend outwardly of the hull, pass through openings in thebase holder 14 and terminate in a threaded end which carries nuts 36 soas to secure the holder against the hull. The enlarged opening aroundthe nut 36 is filled with epoxy 37 as is the area 38 immediatelyadjacent the holder 14, which provides a smooth flare to the hull.Disposed about the upper portion of the pin 19 is a fiber glass flange39 which is secured by machine screws 40 threaded into the holder 14 andhas its upper shoulder 41 bearing against a neoprene gasket 42 to form awaterproof seal against the upper surface of the holder I4. A secondneoprene gasket 43 provides sealing of the pin 19 by being compressedbetween the flange 39 and rectangular pin washer 22.

A reference electrode 44 comprises a hexagonal silver head 45 having acentral internally threaded portion 46 which mates with and is threadedon the upper pin 19 portion. The head 45 has an outwardly extendingflange 47 which has welded thereto the electrode element 48. Theelectrode element is of standard silver-silver chloride and consists oftreated silver gauze, woven of silver wire approximately 10 mils indiameter to a No. 40 mesh. This silver wire is not less than 99.95percent pure silver and the gauze is wrapped in a linch wide fine-wiresaran screen woven of saran wire (copolymer of vinylidene chloride andvinyl chloride) approximately mils in diameter. Teflon spacers 49recessed into the base holder 14 support the electrode element 48horizontal or parallel to the'hull 10. The base holder 14 has anenlarged central recess about the reference electrode and the holdercircumferential recess wall is provided with threads 50. Disposed andthreaded therein is a fiber glass holder cover 51 which is secured by anylon thread lock 52. The holder cover has provided therethrough aplurality of openings 53 to admit the free passage of water into theplenum formed between the cover 51 and the holder 14 so as to immersethe reference electrode in the sea water without the generation ofexcessive turbulance due to the ships motion.

With regard to replacement of the reference electrode, it is quite clearthat a diver merely unscrews the perforated cover 51, then unthreads theelectrode, substitutes a new electrode element and then replaces thecover 51 without disturbing the stuffing gland and the packing.

I claim:

1. In an impressed current cathodic protection system for a ship, areplaceable reference electrode holder structure which comprises:

a conductive hull of such ship,

a metallic silver rod having an insulating coating of epoxy and threadedat both ends,

a watertight means passing through said ships hull and carrying thereinsaid rod and having said threaded ends thereof extending out of and pastsaid watertight means for providing communication of said rod betweenthe interior and the exterior of such ship,

a base holder of electrically insulating material disposed on the outersurface of said hull and having a central enlarged opening through whichsaid rod extends,

means for tightly securing said holder to said hull,

a reference electrode threaded on the end of said rod, said referenceelectrode comprising a silver head portion having a central threadedaperture and an extending flange having welded thereto an electrodeelement formed of layers of silver gauze extending radially outwardly,and

a perforated cover releaseably disposed across and closing said centralenlarged opening to form a plenum having therein said electrode.

2. The structure according to claim 1 further including Teflon plugspacer means carried by said base holder and extending outwardly thereofin abutting relation with said element for support thereof.

3. The structure according to claim 2 further including means forpreventing rotation of said metallic rod during replacement of saidreference electrode.

4. The structure according to claim 1 further including a plurality ofneoprene gaskets disposed about said rod between said head portion andsaid base holder to prevent the entrance of water. 1

5. The structure according to claim 4 wherein said perforated cover is acircular disc whose peripheral wall is threaded to mate with similarthreads on the wall of said central enlarged opening of said baseholder.

6. The structure according to claim 5 further including a layer ofinsulating epoxy between said base holder and said hull.

2. The structure according to claim 1 further including Teflon plugspacer means carried by said base holder and extending outwardly tHereofin abutting relation with said element for support thereof.
 3. Thestructure according to claim 2 further including means for preventingrotation of said metallic rod during replacement of said referenceelectrode.
 4. The structure according to claim 1 further including aplurality of neoprene gaskets disposed about said rod between said headportion and said base holder to prevent the entrance of water.
 5. Thestructure according to claim 4 wherein said perforated cover is acircular disc whose peripheral wall is threaded to mate with similarthreads on the wall of said central enlarged opening of said baseholder.
 6. The structure according to claim 5 further including a layerof insulating epoxy between said base holder and said hull.